The present invention relates to the operation and construction of an ink jet printer device and, in particular, discloses a coil actuated magnetic plate ink jet printer.
Many different types of printing have been invented, a large number of which are presently in use. The known forms of printers have a variety of methods for marking the print media with a relevant marking media. Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc.
In recent years, the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nozzles has become increasingly popular primarily due to its inexpensive and versatile nature.
Many different techniques of ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, xe2x80x9cNon-Impact Printing: Introduction and Historical Perspectivexe2x80x9d, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).
Ink Jet printers themselves come in many different types. The utilisation of a continuous stream ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electro-static ink jet printing.
U.S. Pat. No. 3,596,275 by Sweet also discloses a process of a continuous ink jet printing including the step wherein the ink jet stream is modulated by a high frequency electrostatic field so as to cause drop separation This technique is still utilized by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al)
Piezoelectric ink jet printers are also one form of commonly utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 discloses a piezoelectric push mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element.
Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclosed ink jet printing techniques rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices utilizing the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.
As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction operation, durability and consumables.
The present invention provides an ink jet nozzle assembly formed on a substrate and including a nozzle chamber having a nozzle through which ink from the chamber can be ejected, the nozzle being situated on a portion of the chamber that moves relative to the substrate when the assembly is activated in use.
The present invention further provides an ink jet nozzle assembly including:
a nozzle chamber having an inlet in fluid communication with an ink reservoir and a nozzle through which ink from said chamber can be ejected;
the chamber including a fixed portion and a movable portion configured such that relative movement in an ejection phase reduces an effective volume of the chamber, and alternate relative movement in a refill phase enlarges the effective volume of the chamber;
an actuator connected with the movable portion of the chamber and periodically effecting said relative movement;
the nozzle being formed in the movable portion and the inlet being positioned and dimensioned relative to the nozzle, such that ink is ejected preferentially from the chamber through the nozzle in droplet form in the ejection phase, and ink is alternately drawn preferentially into the chamber from the reservoir through the inlet in the refill phase.
Preferably the fixed portion is mounted on a substrate.
Preferably the actuator is interposed between the substrate or the fixed portion of the chamber and the movable portion of the chamber.
Preferably an inlet passage extends between the inlet and the ink reservoir.
Preferably the inlet passage includes flow restriction means to enhance the preferential ejection of ink from the chamber during the ejection phase in response to the relative movement of the nozzle.
Preferably: the flow restriction means includes a region of reduced effective cross-sectional area relative to the chamber.
Preferably the flow restriction means include wall friction in the inlet passage.
Preferably the ink jet nozzle is manufactured using micro-electro-mechanical-systems (MEMS) techniques.